Muscle Diseases - Bell's palsy

Bell's palsy
is a paralysis of the facial nerve that was first described by Sir
Charles Bell, a Scottish surgeon of the early nineteenth century. It may
affect men and women at any age, though it occurs most commonly between
the ages of 30 and 50. The onset of the facial paralysis may be abrupt:
the patient may awaken one morning unable to move one side of his face.
He can't wrinkle one side of his forehead or raise the eyebrow;
the eye will not close on the affected side, and when attempting to
smile, the face is pulled to the opposite side. Occasionally the patient
may experience discomfort about the ear on the involved side. There is
no difficulty in swallowing, but because the muscles about the corner of
the mouth are weak, drooling is not uncommon, and food may accumulate in
the gutter between gum and lip.

Bell's palsy may affect the branch of the facial nerve that
supplies taste sensation to the anterior part of the tongue and the
branch that supplies a small muscle in the middle ear (the
stapedius
) whose function it is to dampen loud sounds. Depending on the extent to
which the facial nerve is affected, the patient may be unable to
perceive taste on the side of the paralysis and may be unusually
sensitive to sounds, a condition known as
hyperacusis
.

The most probable causes of Bell's palsy are inflammation of the
facial nerve as it passes through a bony canal within the skull or
inflammation of that bony canal with subsequent swelling and compression
of the nerve. It is not uncommon that the patient has a history of
exposure to a cold breeze, such as sleeping in a draft or riding in an
open car. Any patient who has a facial weakness should be carefully
evaluated by a physician, preferably a neurologist, to be quite certain
that there is no other neurologic abnormality. When the diagnosis of
Bell's palsy is certain, some therapeutic measures can be taken.

Treatment

There is no specific treatment for Bell's palsy, but many
physicians recommend massage, application of heat, and exercise of the
weak muscles, either passive (by external manipulation) or active (by
use). These therapeutic measures do not specifically influence the
course of the facial nerve paralysis, but they are thought to be useful
in maintaining tone of the facial muscles and preventing permanent
deformity. Occasionally a V-shaped adhesive tape splint can be applied
to the affected side of the face, from the corner of the mouth to the
temple. Some physicians treat the condition with steroids such as
cortisone, which may hasten recovery if begun at the onset of the
illness.

In treating Bell's palsy, it is important to remember that when
the eyelid does not close normally, the conjunctiva and cornea are not
fully lubricated, and corneal lesions may develop from excessive dryness
or exposure to the air. For this reason, some ophthalmic lubrication may
be recommended by the physician.

About 80 percent of the patients with Bell's palsy recover
completely in a few days or weeks, and about 10 to 15 percent recover
more slowly, over a period of three to six months. The remaining 5 to 10
percent will have some residual facial deformity.

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